Rheumatoid arthritis (RA) is a chronic infl ammatory disease of synovial joints that is associated with cartilage and bone destruction. Death Receptor 3 (DR3), a tumor necrosis factor (TNF) receptor superfamily member, has recently been associated with the pathogenesis of RA. We demonstrate that absence of DR3 confers resistance to the development of adverse bone pathology in experimental antigen-induced arthritis (AIA). DR3 ko mice exhibited a reduction in all histopathological hallmarks of AIA but, in particular, failed to develop subchondral bone erosions and were completely protected from this characteristic of AIA. In contrast, TNF-like protein 1A (TL1A), the ligand for DR3, exacerbated disease in a dose-and DR3-dependent fashion. Analysis of osteoclast number within AIA joint revealed a reduction in areas susceptible to bone erosion in DR3 ko mice, whereas in vitro osteoclastogenesis assays showed that TL1A could directly promote osteoclastogenesis in mouse and man. Treatment with antagonistic anti-TL1A mAb protected animals in a systemic model of RA disease collagen-induced arthritis. We therefore conclude that the DR3 -TL1A pathway regulates joint destruction in two murine models of arthritis and represents a potential novel target for therapeutic intervention in infl ammatory joint disease.

The CD154/CD40 interaction is an important pathway of CD4 T cell help for CD8 T cell responses. In this study, we address the role of CD70, a member of the TNF superfamily and the ligand for the T cell costimulatory receptor CD27, in CD40-mediated priming of CD8 T cells. Using an agonistic anti-CD40 mAb to mimic the CD154/CD40 interaction we demonstrate that the priming of OT-I TCR transgenic or endogenous mouse OVA-specific CD8 T cells is critically dependent on CD70/CD27 interaction. CD70 blockade inhibited CD40-mediated clonal expansion of CD8 T cells and reduced the number of memory CD8 T cells generated. Furthermore, CD70 blockade during the initial priming of CD8 T cells inhibited the ability of memory CD8 T cells to expand in response to a second encounter with Ag. Our data indicate that CD70 expression on APCs plays a key role in CD40-dependent CD8 T cell responses.

The tumor necrosis factor (TNF) superfamily protein TNF-like 1A (TL1A) is the ligand for death receptor 3 (DR3). TL1A is induced on activated dendritic cells (DCs) and its expression has been linked to human inflammatory bowel disease. To address how TL1A might influence intestinal inflammation, we generated transgenic mice that constitutively express TL1A on DCs. TL1A transgenic mice developed striking goblet cell hyperplasia in the ileum that was associated with elevated interleukin (IL)-13 levels in the small intestine. IL-13-and IL-17-producing small intestinal lamina propria T cells were increased in TL1A transgenic mice. TL1A also enhanced regulatory T (Treg) cell turnover in vivo and directly stimulated Treg cell proliferation in vitro.The presence of TL1A attenuated the ability of Treg cells to suppress conventional T cells, an effect that required DR3 signaling in either conventional T cells or Treg cells. Our findings identify mechanisms by which chronic DR3 signaling could promote pathogenesis in inflammatory bowel disease.

This study addresses the relative importance of CD134 (OX40) and CD137 (4‐1BB) in the costimulation of CD4+ and CD8+ T cells under comparable conditions of antigenic stimulation. We demonstrate that CD134 is capable of directly costimulating CD8+ T cells. However, costimulation of CD8+ T cells by CD134 is less potent than that triggered by CD137. The higher costimulatory activity of CD137, when compared with CD134, correlates well with its faster expression kinetics and higher levels on CD8+ T cells. Furthermore, induction of CD137 expression on CD8+ T cells is highly sensitive to low levels of TCR stimulation, which is in contrast with CD134. Conversely, CD134 is more effective than CD137 in costimulating CD4+ T cells. This, however, could not be attributed to differential expression. We also demonstrate that the transient nature of CD134 and CD137 expression on activated CD4+ T cells is the resultof proteolytic shedding. Consistent with the greater ability of CD137 to costimulate CD8+ T cells, stimulation of CD137 in vivo is considerably more effective than CD134 in augmenting anti‐tumor immune responses. Therefore, agents that stimulate signaling via CD137 are likely to be more useful in clinical conditions where highly effective CD8+ CTL responses are required.

Growing evidence points to the potential of agonistic anti-CD40 mAbs as adjuvants for vaccination against cancer. These appear to act by maturing dendritic cells (DCs) and allowing them to prime CD8 cytotoxic T lymphocytes (CTLs). Although it is well established that optimal T-cell priming requires costimulation via B7:CD28, recent studies emphasize the contribution of TNF receptors to this process. To understand how anti-CD40 mAbs trigger effective antitumor immunity, we investigated the role of TNFR superfamily members CD27 and 4-1BB in the generation of this immunity and showed that, although partially dependent on 4-1BB:4-1BBL engagement, it is completely reliant on CD27:CD70 interactions. Importantly, blocking CD70, and to some extent 4-1BBL, during anti-CD40 treatment prevented accumulation of tumor-reactive T cells and subsequent tumor protection. However, it did not influence changes in DC number, phenotype, nor the activity of CTLs once immunity was established. We conclude that CD27: IntroductionInteractions between members of the TNF receptor (TNFR) superfamily and their ligands play an important role in providing costimulation at several stages during the development of an effective antigen-specific CD8 T-cell response. [1][2][3] Early in the response, the ligation of CD40 on dendritic cells (DCs) by its ligand, CD154, induces the maturation of DCs and potentiates their ability to stimulate antigen-specific naive CD8 T cells. [4][5][6] Conversely, the absence of DC maturation, for example, during presentation of self-or tumor-associated antigens, leads to the induction of T-cell tolerance. 7 Thus, antigen presentation by immature DCs maintains peripheral tolerance to self-tissues as well as tumors. Agonistic anti-CD40 mAb, which is a potent mimic of the natural ligand, CD154, has been shown to promote T-cell-mediated immunity in a number of settings, including vaccination, and treatment of tumors. [8][9][10][11] The success achieved with agonistic anti-CD40 mAbs in preclinical models has recently led to clinical evaluation of anti-human CD40 mAbs as a potential treatment for cancer. 12,13 It is assumed that anti-CD40 mAbs trigger the maturation, or licensing of DCs which subsequently leads to the priming of tumor-specific CD8 T cells. Identifying the critical changes in DCs during their CD40-triggered maturation is therefore key to understanding the mechanism of action of anti-CD40 mAbs. CD40-induced maturation of DCs is characterized by an increase in their expression of adhesion and costimulatory molecules, including ICAM-1, B7.1, B7.2, CD70, and 4-1BB ligand (4-1BBL) as well as cytokines. [14][15][16][17][18][19] Although initial antigen-specific cytotoxic T lymphocyte (CTL) activation and proliferation depends on the CD28:B7 engagement, 20,21 subsequent expansion and survival of effector and memory T cells are controlled by additional costimulatory interactions and cytokines. Two receptors that appear central in maintaining CD8 T-cell responses are the TNFR superfamily members 4-1BB (CD137) 3,22...

Human cutaneous dendritic cells (DCs) from epidermal and dermal compartments exhibit functional differences in their induction of CD4+ T-cell and humoral immune responses; however, differences in the regulation of memory CD8+ T-cell responses by human skin DCs remain poorly characterized. We tested the capacity of human Langerhans cells (LCs) and dermal dendritic cells (DDCs) to induce antigen-specific cytokine production and proliferation of memory CD8+ cells. Although tumor necrosis factor-α-matured human DCs from both epidermal and dermal compartments showed efficient potential to activate CD8+ cells, LCs were constitutively more efficient than DDCs in cross-presenting CD8+ epitopes, as well as direct presentation of viral antigen to Epstein-Barr virus-specific CD8+ T cells. LCs showed greater expression of CD70, and blockade of CD70-CD27 signaling demonstrated that superiority of CD8+ activation by epidermal LC is CD70 dependent. This CD70-related activation of CD8+ cells by LCs denotes a central role of LCs in CD8+ immunity in skin, and suggests that regulation of LC CD70 expression is important in enhancing immunity against cutaneous epithelial pathogens and cancer.

Activation of invariant NK T (iNKT) cells with the glycolipid α-galactosylceramide promotes CD8+ cytotoxic T cell responses, a property that has been used to enhance the efficacy of antitumor vaccines. Using chimeric mice, we now show that the adjuvant properties of iNKT cells require that CD40 triggering and Ag presentation to CD8+ T cells occur on the same APCs. We demonstrate that injection of α-galactosylceramide triggers CD70 expression on splenic T cell zone dendritic cells and that this is dependent on CD40 signaling. Importantly, we show that blocking the interaction between CD70 and CD27, its costimulatory receptor on T cells, abrogates the ability of iNKT cells to promote a CD8+ T cell response and abolishes the efficacy of α-GalCer as an adjuvant for antitumor vaccines. These results define a key role for CD70 in linking the innate response of iNKT cells to the activation of CD8+ T cells.

PD-1 checkpoint blockade has revolutionized the field of cancer immunotherapy, yet the frequency of responding patients is limited by inadequate T-cell priming secondary to a paucity of activatory dendritic cells (DC). DC signals can be bypassed by CD27 agonists, and we therefore investigated if the effectiveness of anti-PD-1/L1 could be improved by combining with agonist anti-CD27 monoclonal antibodies (mAb). The efficacy of PD-1/L1 blockade or agonist anti-CD27 mAb was compared with a dual-therapy approach in multiple tumor models. Global transcriptional profiling and flow cytometry analysis were used to delineate mechanisms underpinning the observed synergy. PD-1/PD-L1 blockade and agonist anti-CD27 mAb synergize for increased CD8 T-cell expansion and effector function, exemplified by enhanced IFNγ, TNFα, granzyme B, and T-bet. Transcriptome analysis of CD8 T cells revealed that combination therapy triggered a convergent program largely driven by IL2 and Myc. However, division of labor was also apparent such that anti-PD-1/L1 activates a cytotoxicity-gene expression program whereas anti-CD27 preferentially augments proliferation. In tumor models, either dependent on endogenous CD8 T cells or adoptive transfer of transgenic T cells, anti-CD27 mAb synergized with PD-1/L1 blockade for antitumor immunity. Finally, we show that a clinically relevant anti-human CD27 mAb, varlilumab, similarly synergizes with PD-L1 blockade for protection against lymphoma in human-CD27 transgenic mice. Our findings suggest that suboptimal T-cell invigoration in cancer patients undergoing treatment with PD-1 checkpoint blockers will be improved by dual PD-1 blockade and CD27 agonism and provide mechanistic insight into how these approaches cooperate for CD8 T-cell activation. .